Automated media storage libraries are known for providing cost effective access to large quantities of stored media. Generally, media storage libraries include a large number of storage slots on which are stored portable data storage media. The typical portable data storage media is a tape cartridge, an optical cartridge, a disk cartridge, and the like. One (or more) accessors typically accesses the data storage media from the storage slots and delivers the accessed media to a data storage drive for reading and/or writing data on the accessed media. Suitable electronics operate the accessor(s) and operate the data storage drive(s) to transmit to, and/or to receive data from, an attached on-line host computer system.
In a conventional automated media storage library, the storage slots are arranged in a planar orthogonal arrangement forming a “wall” of storage slots for holding data storage media. The plane may be a flat plane, or may be a cylindrical plane. To double the storage capacity, two “walls” of storage slots may be provided on either side of the accessor.
A number of different companies manufacture automated media storage libraries today, each model displaying various different features. One example is the IBM 3494 Media Storage Library. Some of the automated media storage libraries have dual or multiple accessors to provide a level of redundancy and to enhance performance.
In data storage and retrieval systems it is desirable to store vital product data (“VPD”) in a single location to simplify update and backup of such data. By “vital product data” Applicant means system information that must be maintained in nonvolatile storage. At least one copy of such system information must be maintained in nonvolatile memory because this information is essential to the operation of, for example, a data storage and retrieval system. Such VPD includes configuration data, calibration data, part number(s) and serial number(s) for associated assemblies, statistical performance data, and the like.
In prior art data storage and retrieval systems, a single controller operates all aspects of the system. In contrast, Applicant's data storage and retrieval system utilizes a distributed control network which includes a plurality of nodes. Applicant has found it desirable to cache VPD on one or more nodes of that distributed control network. In addition to caching a copy of the VPD at one or more nodes disposed in Applicant's distributed control network, it is also necessary to update this VPD from time to time.
One node in Applicant's distributed control network may require, for example, simple network management protocol (SNMP) code to communicate with a remote host computer. That SNMP node may require nonvolatile configuration data, including host names and/or host IP addresses. A communication failure within the distributed control network should not prevent the SNMP node from communicating with a host because error reporting is one of the SNMP functions.
However, providing hard drives or battery-backup RAM at every node, such as the SNMP node, is costly and impractical. What is needed is a method to maintain and update VPD cached at one or more remote nodes in Applicant's distributed control network.